The present invention relates to a method of producing a ring of abrasive sheet elements from which to form a rotary brush comprising a hub and a ring of abrasive sheet elements substantially projecting from and connected integrally to the hub.
Rings of abrasive elements of brushes of the above type are known, from Italian Patent n. 219581 filed on Feb. 23, 1990 by the present Applicant, to be formed by first forming a number of abrasive sheet elements from reels of abrasive material in strip form; forming the abrasive elements into an orderly succession positioned on edge; arranging the abrasive elements in a ring directly about the hub; and bonding the ring integrally to the hub.
The sheet elements are arranged about the hub by dividing the orderly succession into a number of rows of sheet elements, each row of a length substantially equal to the mean circumference of the ring being produced; and each row of sheet elements is taken manually and gradually wound, again manually, about the hub by skilled workers using specially designed equipment.
Though used, the above known method involves several drawbacks.
In particular, the need for skilled labour and specially designed equipment results in fairly high manufacturing cost and low output; while the brushes so formed are invariably of inconsistent quality. That is, before being bonded to the hub, the sheet elements are subject to slippage, thus resulting in loss of symmetry and impaired efficiency of the finished brush, often to the extent of the brush being rejected, thus further reducing output.